An inflammation of the lungs caused by microscopic grains of certain types of rock.

*NOTE* This word was actually coined in a deliberate attempt to be the longest word in the english language, although you would be hard-pressed to find it in the language dictionary as it is a medical/scientific term.

"Dude, now that I've learned how to spell antidisestablishmentarianism, what am I going to do to make people think I'm smart?"

"Quiet man, I'm trying to name this condition we discovered today. Its an inflammation of the lungs caused by microscopic grains of certain types of rock."

"Hey, I smell opportunity! How long could we make this word?"

"Pretty long...I suppose we could stretch it to pneumonoultramicroscopicsilicovolcanoconiosis"

A factitious word alleged to mean "a lung disease caused by the inhalation of very fine silica dust" but occurring chiefly as an instance of a very long word. (Definition retrieved from Oxford English Dictionary)

Pneumonoultramicroscopicsilicovolcanoconiosis is notable for causing respiratory problems as well as unnecessary fatigue and frustration at spelling bees.